docs: def update_metadata(self, dataset_identifier, update_fields, content_type="json"):
          '''
          Update the metadata for a particular dataset.
              update_fields is a dictionary containing [metadata key:new value] pairs.
  
          This method performs a full replace for the key:value pairs listed in `update_fields`, and
          returns all of the metadata with the updates applied.
          '''
          resource = _format_old_api_request(dataid=dataset_identifier, content_type=content_type)
          return self._perform_update("put", resource, update_fields)